Minimizing wastes     

Abelson PH 《Science (New York, N.Y.)》1994,265(5168):11

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The Structure of Nature's Solvent: Water     

Colson SD  Dunning TH 《Science (New York, N.Y.)》1994,265(5168):43-44

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Magnetic energy storage     

Abelson PH 《Science (New York, N.Y.)》1994,266(5182):11

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The entrepreneurial twist     

Panem S 《Science (New York, N.Y.)》1994,263(5151):1299

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Environmental test case     

Humphrey SR 《Science (New York, N.Y.)》1994,265(5174):976-977

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National institute for science and technology     

Abelson PH 《Science (New York, N.Y.)》1994,264(5162):1063

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Even a robot cricket always gets her mate     

Bains S 《Science (New York, N.Y.)》1994,266(5192):1809

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The effect of intra-ruminal selenium pellets on growth rate, lactation and reproductive efficiency in dairy cattle     

Wichtel JJ  Craigie AL  Varela-Alvarez H  Williamson NB 《New Zealand veterinary journal》1994,42(6):205-210

In each of two dairy herds (A and B), rising yearling heifers (Trial 1) and adult cows (Trial 2) were assigned to three treatment groups. Untreated animals were compared to animals treated with either two or four intra-ruminal pellets containing 3 g of elemental selenium. The administration of pellets at the recommended dose (two pellets per animal) was effective in elevating whole blood glutathione peroxidase activity and selenium concentration to over 10 times those of control animals. In Trial 1, a 15% response in liveweight gain (p<0.001) occurred in yearling heifers in the herd with the lowest pre-treatment selenium status. In Trial 2, cows receiving two pellets produced a greater milk volume (p=0.06) and more milk solids (p=0.02) than untreated controls; an increase in volume of 5.4% and 8%, and in milk solids of 6.5% and 6.4%, were noted in herds A and B respectively. There was a trend towards decreasing somatic cell counts in milk from the treated cows when compared to controls, the four-pellet group in Herd A and the two-pellet group in Herd B being significantly different from their respective control group. No between-group differences were noted in calving-first service or calving-conception intervals, nor in the proportion of animals pregnant to first or all services. The administration of selenium at twice the recommended dose rate yielded no additional response above that noted after the administration of the recommended dose. The results of this study support the use of currently recommended Ministry of Agriculture and Fisheries selenium reference ranges in cattle for the prediction of a response to supplementation.  相似文献   

Seroprevalence of Brucella ovis infection in commercial ram flocks in the Tamworth area     

Sergeant ES 《New Zealand veterinary journal》1994,42(3):97-100

Commercial ram flocks in the Tamworth area of northern New South Wales were surveyed to estimate the proportion of flocks, and rams, infected with Brucella ovis. The flock prevalence (percentage of flocks containing seropositive rams) of 9.1% for Merino flocks was significantly lower than that for British-breed flocks (43.8%, p=0.006) and mixed-breed flocks (46.7%, p=0.017). The mean flock prevalence over all flock types was 32.9%. These estimates were supported by data obtained from diagnostic testing for brucellosis carried out during the previous 6 years. The seroprevalence in rams was 10.8% overall, 2.5% for Merinos, 19% for Border Leicester and 26% for Dorset rams. Within infected flocks, the estimated prevalences were 21%, 65% and 67% for Merinos, Border Leicester and Dorset rams respectively. The seroprevalence in Merino rams was significantly lower than that for both other breeds (p<0.001) for all flocks and in infected flocks. There was no apparent association between age and serological status, or age and the prevalence of epididymitis.  相似文献   

Heterosis, maternal and direct effects for postweaning growth traits and carcass performance in rabbit crosses     

Afifi EA  Khalil MH  Khadr AF  Youssef YM 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》1994,111(1-6):138-147

SUMMARY: A crossbreeding experiment was carried out in Egypt using a local breed (Baladi Red, BR) and New Zealand White (NZ) to estimate direct heterosis, maternal additive effects and direct sire effects on some growth and carcass traits in rabbits. Data of body weight (at 5, 6, 8, 10, 12 weeks) and daily gains (at intervals of 5-6, 6-8, 8-10, and 10-12 weeks) on 2153 weaned rabbits were collected. Carcass performance at 12 weeks of age (weight and percentages of carcass, giblets, head, fur, blood and viscera) on 213 male rabbits was evaluated. Estimates of coefficients of variation (CV) for most growth and carcass traits were high and ranged from 10.0 to 40.2%. Sire-breed was of considerable importance in the variation of growth traits and some carcass traits, while dam-breed contributed little. Sire-breed × dam-breed interaction affected (P<0.01 or P<0.001) most body weights and gains studied, while it contributed little to the variation of carcass traits. The purebred NZ resulted in rabbits with heavier weights and carcass and with lighter non-edible carcass (blood and viscera) compared to the BR. Heterosis percentages for most growth traits were significant and ranged from 2.5% to 5.0% for body weights and from 0.7% to 9.5% for daily gains. Insignificant positive direct heterosis was observed for most carcass traits. Crossbred rabbits from NZ sires with BR dams were superior to from the reciprocals. Maternal-breed effects on most weights and gains were insignificant, while sire-breed contrasts for some weights and gains proved significant. Postweaning growth and carcass performances of BR-mothered rabbits generally surpassed the NZ mothered, while NZ-sired rabbits were superior at later ages. High edible carcass was observed for BR-sired rabbits, while more non-edible carcass wastes (blood and viscera) for NZ-sired rabbits. Maternal-breed effects appeared to be less important than paternal-breed effects in influencing most weights, gains and carcass traits studied. ZUSAMMENFASSUNG: Heterosis, maternale und direkte Wirkungen bei Wachstums- und Schlachtk?rpermerkmalen in Kaninchenkreuzungen Der Kreuzungsversuch wurde mit lokalen ?gyptischen Rassen (BR) und Neuseeland Wei?en (NZ) zur Sch?tzung direkter Heterosis, maternaler additiver Wirkungen, direkter Vater-Wirkung auf einige Wachstums- und Schlachtk?rpermerkmale von Kaninchen durchgeführt. Angaben über K?rpergewicht (5, 6, 8, 10, 12 Wochen) und Zuwachs (Intervalle 5 bis 6, 6 bis 8, 8 bis 10, 10 bis 12 Wochen) wurden von 2153 abgesetzten Kaninchen gewonnen. Die Schlachtk?rperleistungen bei 12 Wochen Alter (Gewicht und Anteil von Schlachtk?rper, Kopf, Pelz, Blut und Innereien) stammen von 213 m?nnlichen Kaninchen. Sch?tzungen der Variationskoeffizenten (CV) für meiste Wachstums- und Schlachtk?rpermerkmale waren hoch und bewegten sich zwischen 10 und 40,2%. Vaterrasse hatte erheblichen Einflu? auf Unterschiede in Wachstumsrate und einige Schlachtk?rpermerkmale, w?hrend die Mutterrasse weniger beigetragen hat. Interaktion zwischen beiden beeinflu?te die meisten K?rpergewichts- und Zuwacnsleistungen, w?hrend sie wenig zur Variabilit?t der Schlachtk?rpermerkmale beigetragen hat. Reinrassige NZ waren schwerer und hatten weniger nicht nutzbare Schlachtk?rperteile (Blut und Eingeweide) verglichen mit BR. Heterosis-Prozente für die meisten Wachstumsmerkmale waren signifikant und schwankten zwischen 2,5 und 5% für K?rpergewicht, 0,7 bis 9,5% für Zuwachs. Insignifikante positive direkte Heterosis wurde für die meisten Schlachtk?rpermerkmale beobachtet. Kreuzungskaninchen von NZ V?tern waren den reziproken überlegen. Maternale Wirkungen auf meiste Gewichtsmerkmale waren insignifikant, w?hrend Vaterrassenkontraste hierfür signifikant waren. Zuwachs- und Schlachtk?rperleistung von BR ges?ugten Kaninchen haben im allgemeinen die von NZ ges?ugten übertroffen, w?hrend von NZ B?cken gezeugte in sp?teren Altersabschnitten überlegen waren. Hohe Werte für Schlachtk?rper wurden für BR ges?ugte Kaninchen gefunden, w?hrend mehr nicht verzehrbare Abf?lle (Blut und Eingeweide) bei NZ gezeugten vorhanden war. Maternale Rassenwirkungen schienen weniger wichtig als paternale zu sein.  相似文献